Ferrari's Formula One championship leader Fernando Alonso lapped almost half a minute off the pace in a rain-lashed and meaningless first practice session for the Belgian Grand Prix on Friday.

Sauber's Kamui Kobayashi ended up with his name on top of the timing screens after a fastest lap of 2min11.389 but the Japanese was among a small minority to get into double figures with his lap tally.

Most of the rest stayed in their garages for long periods of the morning session as the classic Ardennes track took a steady soaking and prevented any serious attempt by teams to gain data and try out new developments.

Alonso, who has a 40 point lead over Red Bull's Australian Mark Webber after 11 of this seasons’ 20 races, ended up 22nd and with a time 29.360 seconds slower than Kobayashi.

Kimi Raikkonen, winner four times at his favourite circuit and a good bet for victory with Lotus on Sunday, was 23rd and 35.191 off the pace but will be equally unperturbed by the timesheets.

Raikkonen's race lap record, set with McLaren in 2004, is 1min45.108.

Venezuelan Pastor Maldonado lapped second fastest for Williams while Australian Daniel Ricciardo, with Toro Rosso, was third as cars hit the track again in the first practice session after the long August break.

Alonso's Brazilian team mate Felipe Massa was the only driver to end the morning without setting a lap time and he pulled up at the end of the session with smoke billowing from his Ferrari's engine.

Michael Schumacher, marking his 300th Grand Prix with a new helmet design, slid heavily through Eau Rouge without misfortune. Others also aquaplaned in early runs before the weather improved slightly later on.

Force India's Nico Hulkenberg was one of them.

“There's so much water out there, going into and out of Eau Rouge,” he commented. “It's pretty dangerous out there.” - Reuters